Friday, October 16, 2009

No longer sure if PSA screening for possible prostate cancer is such a good idea

Irish Times That's Men Column published 13th October 2009: I used to think it a very good thing to go off and have a PSA test done every year to screen for prostate cancer. Now I'm not so sure. Doctors seem divided on the value of the test for screening. Some suggest it could do more harm than good when used on men who don't already have other symptoms.

PSA stands for prostate specific antigen, a protein produced by the prostate gland. Higher than normal levels of PSA in the blood can indicate the presence of prostate cancer.

Screening for PSA levels involves a simple blood test - and it has seemed to me that if you are a man above middle age it's wise to get it done every year. Now I read of research reported in the Archives of Internal Medicine which raises all sorts of questions in my mind, some of them unpleasant.

One study at the University of Sydney found that screening 1,000 men every year between ages of 40 and 69 reduces the number of deaths from prostate cancer by two - yes, two - by the age of 85. Meanwhile, about 640 will have died from other causes. Kirsten Howard of the University of Sydney made the remarkable statement to HealthDay News that men who are screened are two to four times more likely to be diagnosed with prostate cancer than those who are not screened - yet the death rates for both groups are similar.

The difficulty is that the PSA test cannot predict which prostate cancers are agressive and need to be treated and which are developing so slowly that the patient will die of other causes long before the cancer kills him. Because of the uncertainty, people may be treated who don't need to be treated and this can have side effects such as impotence and incontinence.

That's scary.

The dilemmas posed by the PSA test have surfaced among Irish doctors too. In a letter to the Irish Medical News earlier this year, Dr Ray O'Connor wrote that  "PSA is a far from ideal screening test and its general use in asymptomatic men is a very questionable practice, I feel."

Professor Tom Fahey in a letter referred to "the ongoing dilemma of how best to treat men with localised prostate cancer - watchful waiting, radiotherapy or radical prostatectomy, because of the substantial trade-offs involved in terms of improved survival versus common side-effects such as urinary incontinence and sexual dysfunction."

Last March, the Irish Medical News reported on a symposium organised by the Royal College of Physicians of Ireland in association with the National Cancer Screening Service (NCSS). Dr Alan Smith, consultant in public health medicine from the NCSS told the symposium that population screening for prostate cancer could do more harm than good, the newspaper reported. Population screening  involves screening everybody in a particular group in the way that Breastcheck, for instance, offers screening to all women aged 50-64 in 17 counties.

While population screening for prostate cancer "would undoubtedly identify more cancers in men, it is also likely that a population approach to screening would expose the majority of men participating in such a programme to unnecessary harms. Unnecessary biopsies and the complications of treatment can cause side-effects including impotence and incontinence."

I have quoted the views of doctors at some length here because it is the fact that these views are coming from doctors - including doctors in respectable research institutions - that impresses me.

If you are thinking of having a PSA test I suggest you discuss these issues with your own doctor who knows more about this than I do. Those men whose lives were saved by a PSA test would certainly think it worthwhile, whatever the findings mentioned above.

Work is currently being done by the Prostate Cancer Research Consortium to find a more accurate test to address these issues. The consortium includes Trinity College Dublin, the Royal College of Surgeons in Ireland, Dublin City University and the hospitals linked to these institutions.

Meanwhile, I think we need a debate on this topic and I hope that medical and non-medical people will now weigh in.